| 摘要: |
| 针对现有正交频分复用（Orthogonal Frequency Division Multiplexing，OFDM）系统信道估计和迭代检测算法中频谱效率低和鲁棒性差等问题，提出了一种基于酉近似消息传递和叠加导频的信道估计与联合检测方法。首先，在软调制/解调中叠加导频对正交幅度调制的星座点进行预处理，检测时将叠加的导频作为频域符号的先验分布，利用置信传播算法进行调制和解调，实现检测模型的简化。然后，应用因子图-消息传递算法对OFDM传输系统和信道进行建模和全局优化，引入酉变换加强信道估计算法的鲁棒性。最后，建立OFDM仿真环境对现有方法进行仿真分析。仿真结果表明，相对于现有的独立导频类算法，所提算法能够以相同复杂度显著提升OFDM系统的频谱效率和鲁棒性。 |
| 关键词: 正交频分复用(OFDM) 稀疏信道估计 叠加导频 近似消息传递 因子图 |
| DOI：10.20079/j.issn.1001-893x.220530004 |
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| 基金项目:河南省科技攻关项目；河南省青年骨干教师培养计划（2020GGJS195） |
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| OFDM Joint Channel Estimation and Detection under Superimposed Pilots |
| ZHAO Heng,YUAN Zhengdao,LIU Fei,CUI Jianhua |
| (1.School of Information Engineering and Artificial Intelligence,Open University of Henan,Zhengzhou 450001,China;2.School of Geoscience and Technology,Zhengzhou University,Zhengzhou 450001,China;3.School of Physics and Electronic Information,Luoyang Normal University,Luoyang 471934,China) |
| Abstract: |
| For the problems such as low spectrum efficiency and poor robustness of the existing orthogonal frequency division multiplexing(OFDM) channel estimation and iterative detection algorithms,a channel estimation and joint detection algorithm based on unitary approximation message passing and superimposed pilot frequencies is proposed.Firstly,the unitary transformation is adopted in the channel estimation to solve the problem of robustness inherent in the approximate message passing algorithm.Then,the frequency domain superposition pilot is introduced for the initial estimation of the channel.In the soft modulation/demodulation,the superposition pilot is applied to the quadrature amplitude modulation(QAM) constellation points as the prior distribution of the frequency domain symbols,so as to avoid the increasement of complexity.Simulation results show that the proposed algorithm can significantly improve the spectral efficiency and robustness of OFDM systems with the same complexity compared with the existing independent pilot algorithms. |
| Key words: orthogonal frequency division multiplexing(OFDM) sparse channel estimation superimposed pilot approximate message passing factor graph |
